Feather ESP32-C6 Fails with code.circuitpython.org USB Connection

[eightycc]

CircuitPython version and board name

Adafruit CircuitPython 10.0.0-alpha.2 on 2025-04-04; Adafruit Feather ESP32-C6 4MB Flash No PSRAM with ESP32C6

Code/REPL

n/a

Behavior

USB connection using code.circuitpython.org succeeds, but directory displays garbage. Subsequently disconnecting from code.circuitpython.org, connecting with minicom, then hitting ctrl-D results in:

soft reboot

Auto-reload is off.
Running in safe mode! Not running saved code.

You are in safe mode because:
CircuitPython core code crashed hard. Whoops!
Hard fault: memory access or instruction error.
Please file an issue with your program at github.com/adafruit/circuitpython/issues.
Press reset to exit safe mode.

Press any key to enter the REPL. Use CTRL-D to reload.

Description

Testing with CP 9.2.7 succeeds. code.circuitpython.org works as expected. No crash occurs.

Additional information

No response

[eightycc]

Additional notes:

• Flash completely erased between tests
• Similar behavior with Thonny

[eightycc]

Bisecting 62 commits from tags 9.2.7 to 10.0.0-alpha.2.

[eightycc]

Regression introduced in this PR: #10208

I don't think that this PR is the root cause, instead it somehow affects the generated code to bring out the bug.

[eightycc]

code.circuitpython.org sends a small Python program to display the root directory:

import os
import time
contents = os.listdir("/")
for item in contents:
    result = os.stat("/" + item)
    print(item, result[0], result[6], result[9])

This triggers one of two failures, one is trapped by a hardware breakpoint on _panic_handler, the other is trapped by a hardware breakpoint on mp_obj_new_exception_msg.

(gdb) hb mp_obj_new_exception_msg
Hardware assisted breakpoint 2 at 0x4200fcd4: file ../../py/objexcept.c, line 491.
(gdb) hb _panic_handler
Hardware assisted breakpoint 3 at 0x40800102: file /Users/rabeles/Development/cp-development/issue-10296/cp-repo-10296/ports/espressif/esp-idf/components/riscv/vectors.S, line 141.

The mp_obj_new_exception_msg case:

Thread 4 "main" hit Breakpoint 2, mp_obj_new_exception_msg (exc_type=0x4215d8f0 <mp_type_NotImplementedError>, msg=0x421603e4 <translation464>)
    at ../../py/objexcept.c:491
491	    return mp_obj_new_exception_msg_varg(exc_type, msg);
(gdb) bt
#0  mp_obj_new_exception_msg (exc_type=0x4215d8f0 <mp_type_NotImplementedError>, msg=0x421603e4 <translation464>) at ../../py/objexcept.c:491
#1  0x4201a5d8 in mp_execute_bytecode (code_state=code_state@entry=0x408403fc, inject_exc=inject_exc@entry=0x0)
    at build-adafruit_feather_esp32c6_4mbflash_nopsram/genhdr/qstrdefs.generated.h:1977
#2  0x420107c2 in fun_bc_call (self_in=0x40840df0, n_args=<optimized out>, n_kw=0, args=0x0) at ../../py/objfun.c:271
#3  0x42057c34 in parse_compile_execute (source=source@entry=0x40836f30, input_kind=input_kind@entry=MP_PARSE_FILE_INPUT, 
    exec_flags=exec_flags@entry=17, result=result@entry=0x0) at ../../shared/runtime/pyexec.c:161
#4  0x42057e54 in pyexec_raw_repl () at ../../shared/runtime/pyexec.c:628
#5  0x4201faf6 in run_repl (safe_mode=SAFE_MODE_NONE) at ../../main.c:944
#6  main () at ../../main.c:1103
(gdb) frame 1
#1  0x4201a5d8 in mp_execute_bytecode (code_state=code_state@entry=0x408403fc, inject_exc=inject_exc@entry=0x0)
    at build-adafruit_feather_esp32c6_4mbflash_nopsram/genhdr/qstrdefs.generated.h:1977
1977	TRANSLATION("opcode", 464)
(gdb) info locals
obj = <optimized out>
ip = 0x40840f4e "\204@lib"
sp = 0x40840410
qstr_table = 0x40840e50
obj_shared = <optimized out>
nlr = {prev = 0x40836db0, ret_val = 0x1, jmpbuf = {4648845097327239222, 4648337483707452912, 0, 12884901898, 4, 0, 4648677850193330176, 
    4755954091266444018, 4648282800183798976, 2148566003728, -4294967281, 4756283206020478656, 4648282800183799008, 4612545605674430480, 
    4648856039796506639, 1082393596, 1082393616, 4648845250838659072, 0, 4294967298, 0, 4648845182119182346, 4648856039796506624, 1082393652, 
    7, 271665213440, 4648339234971713539, 4756091117903132018, 1082355040, 171798691840, 10, 4648856040878900220, 1082393596, 0, 
    4648845372180018768, 4294967298, 1082275408, 0}, pystack = 0x4084043c}
entry_table = {0x4201a5c4 <mp_execute_bytecode+1510> <repeats 16 times>, 0x4201a5e6 <mp_execute_bytecode+1544>, 
  0x4201a386 <mp_execute_bytecode+936>, 0x4201a528 <mp_execute_bytecode+1354>, 0x4201b18c <mp_execute_bytecode+4526>, 
  0x4201a44a <mp_execute_bytecode+1132>, 0x4201b158 <mp_execute_bytecode+4474>, 0x4201b088 <mp_execute_bytecode+4266>, 
  0x4201b008 <mp_execute_bytecode+4138>, 0x4201b03a <mp_execute_bytecode+4188>, 0x4201af46 <mp_execute_bytecode+3944>, 
  0x4201af14 <mp_execute_bytecode+3894>, 0x4201a556 <mp_execute_bytecode+1400>, 0x4201a72e <mp_execute_bytecode+1872>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a920 <mp_execute_bytecode+2370>, 0x4201a8bc <mp_execute_bytecode+2270>, 0x4201a65a <mp_execute_bytecode+1660>, 
  0x4201a4e0 <mp_execute_bytecode+1282>, 0x4201a496 <mp_execute_bytecode+1208>, 0x4201b1e0 <mp_execute_bytecode+4610>, 
  0x4201b0f0 <mp_execute_bytecode+4370>, 0x4201b0ba <mp_execute_bytecode+4316>, 0x4201afaa <mp_execute_bytecode+4044>, 
  0x4201af74 <mp_execute_bytecode+3990>, 0x4201ab88 <mp_execute_bytecode+2986>, 0x4201ab5a <mp_execute_bytecode+2940>, 
  0x4201ab34 <mp_execute_bytecode+2902>, 0x4201aaf6 <mp_execute_bytecode+2840>, 0x4201aab6 <mp_execute_bytecode+2776>, 
  0x4201aa30 <mp_execute_bytecode+2642>, 0x4201aa6c <mp_execute_bytecode+2702>, 0x4201a9da <mp_execute_bytecode+2556>, 
  0x4201a9ac <mp_execute_bytecode+2510>, 0x4201a95a <mp_execute_bytecode+2428>, 0x4201a87c <mp_execute_bytecode+2206>, 
  0x4201a83c <mp_execute_bytecode+2142>, 0x4201a246 <mp_execute_bytecode+616>, 0x4201a7fc <mp_execute_bytecode+2078>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201ac7a <mp_execute_bytecode+3228>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201ae60 <mp_execute_bytecode+3714>, 0x4201ae38 <mp_execute_bytecode+3674>, 
  0x4201ae10 <mp_execute_bytecode+3634>, 0x4201ad76 <mp_execute_bytecode+3480>, 0x4201ad54 <mp_execute_bytecode+3446>, 
  0x4201ad98 <mp_execute_bytecode+3514>, 0x4201a2be <mp_execute_bytecode+736>, 0x4201a2be <mp_execute_bytecode+736>, 
  0x4201ac2a <mp_execute_bytecode+3148>, 0x4201abb6 <mp_execute_bytecode+3032>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a632 <mp_execute_bytecode+1620>, 0x4201a652 <mp_execute_bytecode+1652>, 0x4201b216 <mp_execute_bytecode+4664>, 
  0x4201b20c <mp_execute_bytecode+4654>, 0x4201b14c <mp_execute_bytecode+4462>, 0x4201b138 <mp_execute_bytecode+4442>, 
  0x4201afde <mp_execute_bytecode+4096>, 0x4201aef4 <mp_execute_bytecode+3862>, 0x4201aece <mp_execute_bytecode+3824>, 
  0x4201af42 <mp_execute_bytecode+3940>, 0x4201aea8 <mp_execute_bytecode+3786>, 0x4201ae90 <mp_execute_bytecode+3762>, 
  0x4201ad10 <mp_execute_bytecode+3378>, 0x4201ac4a <mp_execute_bytecode+3180>, 0x4201ac1e <mp_execute_bytecode+3136>, 
  0x4201ac04 <mp_execute_bytecode+3110>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201ab22 <mp_execute_bytecode+2884>, 0x4201b39e <mp_execute_bytecode+5056>, 0x4201a7d0 <mp_execute_bytecode+2034>, 
  0x4201a7a2 <mp_execute_bytecode+1988>, 0x4201a75e <mp_execute_bytecode+1920>, 0x4201a404 <mp_execute_bytecode+1062>, 
  0x4201a3d0 <mp_execute_bytecode+1010>, 0x4201a724 <mp_execute_bytecode+1862>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a6f8 <mp_execute_bytecode+1818> <repeats 64 times>, 
  0x4201a6e4 <mp_execute_bytecode+1798> <repeats 16 times>, 0x4201a6b4 <mp_execute_bytecode+1750> <repeats 16 times>, 
  0x4201a6a2 <mp_execute_bytecode+1732>, 0x4201a6a2 <mp_execute_bytecode+1732>, 0x4201a6a2 <mp_execute_bytecode+1732>, 
  0x4201a6a2 <mp_execute_bytecode+1732>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a590 <mp_execute_bytecode+1458> <repeats 35 times>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>, 
  0x4201a5c4 <mp_execute_bytecode+1510>, 0x4201a5c4 <mp_execute_bytecode+1510>}
fastn = <optimized out>
exc_stack = <optimized out>
exc_sp = 0x4084042c
outer_dispatch_loop = <optimized out>
dispatch_loop = <optimized out>
(gdb) print code_state
$1 = (mp_code_state_t *) 0x408403fc
(gdb) print *code_state
$2 = {fun_bc = 0x40840df0, ip = 0x40840f4d "\017\204@lib", sp = 0x4084040c, n_state = 10, exc_sp_idx = 0, 
  old_globals = 0x408236f0 <mp_state_ctx+160>, state = 0x40840410}

The _panic_handler case:

Thread 4 "main" hit Breakpoint 3, _panic_handler ()
    at /Users/rabeles/Development/cp-development/issue-10296/cp-repo-10296/ports/espressif/esp-idf/components/riscv/vectors.S:141
141	    save_general_regs RV_STK_FRMSZ
(gdb) bt
#0  _panic_handler ()
    at /Users/rabeles/Development/cp-development/issue-10296/cp-repo-10296/ports/espressif/esp-idf/components/riscv/vectors.S:141
#1  0x4200fb6c in exc_add_strn (data=0x40836b40, str=0x3c2007a3 "", len=24) at ../../py/objexcept.c:523
#2  0x420016dc in mp_print_strn (print=print@entry=0x40836b38, str=0x3c2007a3 "", len=24, flags=<optimized out>, fill=<optimized out>, 
    width=<optimized out>) at ../../py/mpprint.c:103
#3  0x42001d2c in mp_vprintf (print=print@entry=0x40836b38, fmt=0x40836af7 "q' is not defined", 
    fmt@entry=0x40836af0 "name '%q' is not defined", args=0x40836bac, args@entry=0x40836ba8) at ../../py/mpprint.c:483
#4  0x42001f2e in mp_vcprintf (print=print@entry=0x40836b38, compressed_fmt=compressed_fmt@entry=0x421605d4 <translation436>, 
    args=args@entry=0x40836ba8) at ../../py/mpprint.c:615
#5  0x4200fca2 in mp_obj_new_exception_msg_vlist (exc_type=0x4215d9c8 <mp_type_NameError>, fmt=0x421605d4 <translation436>, 
    args=args@entry=0x40836ba8) at ../../py/objexcept.c:582
#6  0x4200a6e6 in mp_raise_msg_vlist (exc_type=<optimized out>, fmt=<optimized out>, argptr=argptr@entry=0x40836ba8) at ../../py/runtime.c:1805
#7  0x4200a702 in mp_raise_msg_varg (exc_type=<optimized out>, fmt=<optimized out>) at ../../py/runtime.c:1813
#8  0x4200a770 in mp_load_global (qst=59472) at build-adafruit_feather_esp32c6_4mbflash_nopsram/genhdr/qstrdefs.generated.h:1949
#9  0x4200a7a6 in mp_load_name (qst=<optimized out>) at ../../py/runtime.c:232
#10 0x4201a3b2 in mp_execute_bytecode (code_state=code_state@entry=0x408403fc, inject_exc=inject_exc@entry=0x0) at ../../py/vm.c:406
#11 0x420107c2 in fun_bc_call (self_in=0x40840df0, n_args=<optimized out>, n_kw=0, args=0x0) at ../../py/objfun.c:271
#12 0x42057c34 in parse_compile_execute (source=source@entry=0x40836f30, input_kind=input_kind@entry=MP_PARSE_FILE_INPUT, 
    exec_flags=exec_flags@entry=17, result=result@entry=0x0) at ../../shared/runtime/pyexec.c:161
#13 0x42057e54 in pyexec_raw_repl () at ../../shared/runtime/pyexec.c:628
#14 0x4201faf6 in run_repl (safe_mode=SAFE_MODE_NONE) at ../../main.c:944
#15 main () at ../../main.c:1103
(gdb) frame 13
#13 0x42057e54 in pyexec_raw_repl () at ../../shared/runtime/pyexec.c:628
628	        int ret = parse_compile_execute(&line, MP_PARSE_FILE_INPUT, EXEC_FLAG_PRINT_EOF | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
(gdb) info locals
ret = 1082396774
line = {alloc = 176, len = 155, 
  buf = 0x40840d40 "\nimport os\nimport time\ncontents = os.listdir(\"/\")\nfor item in contents:\n    result = os.stat(\"/\" + item)\n    print(item, result[0], result[6], result[9])\n\n", fixed_buf = false}
raw_repl_reset = <optimized out>
(gdb) 

[tannewt]

Please retest this with this fix: #10291

[dhalbert]

This is subsumed by #10298.